Investigating the regulation of nuclear calcium oscillation in plant endosymbiosis

Grubb, Lauren (2022) Investigating the regulation of nuclear calcium oscillation in plant endosymbiosis. Doctoral thesis, University of East Anglia.

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Abstract

Plants associate with beneficial microorganisms such as nitrogen-fixing bacteria, rhizobia, or arbuscular mycorrhizal (AM) fungi to access nutrients in a biologically available form. Successful colonization results in de novo organogenesis of a nodule structure for symbiotic nitrogen fixation or formation of a branched arbuscule structure in root cortical cells for AM fungi. Following perception of lipochitooligosaccharide Nod factors or short-chain chitooligosaccharide Myc factors, respectively, an important early signaling events in both symbiotic associations is the generation of nuclear calcium (Ca2+) oscillation at the nuclear envelope. This requires three nuclear-localized ion channels, DOES NOT MAKE INFECTIONS1 (DMI1), cyclic nucleotide gated channel 15 (CNGC15) a/b/c and a SERCA type ATPase, MCA8. While much is known about Nod and Myc factor perception as well as the requirement for these channels at the nuclear envelope, it is thus far unclear how these channels are activated.

This work presents a novel player in the common symbiosis signaling pathway, a kinase termed AUK. Using CRISPR-Cas9 experiments in M. truncatula hairy roots, AUK was shown to be required for nodulation. Overexpression of AUK in hairy roots as well as a gain of-function EMS mutant resulted in spontaneous nuclear Ca2+ oscillation, and the generation of spontaneous nodule-like structures. In addition, there was increased nodulation and AM colonization upon inoculation with the respective symbionts, indicating an important role for AUK within the common symbiosis signaling pathway. Further epistasis analysis also indicated a role for AUK upstream of DMI1. Finally, preliminary evidence for a mechanism by which AUK may be activating the nuclear Ca2+ oscillation is investigated.

Overall, this thesis presents a novel player in the common symbiosis pathway and provides insight into a possible mechanism for activation of nuclear Ca2+ oscillation involved in plant association with beneficial symbiotic microorganisms.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	James Tweddle
Date Deposited:	23 Jun 2023 15:11
Last Modified:	23 Jun 2023 15:11
URI:	https://ueaeprints.uea.ac.uk/id/eprint/92489
DOI:

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